Smoke control system

ABSTRACT

A smoke control system utilizing an afterburner and a filter formed from expanded blast furnace slag, the filter being in the form of a cartridge carried with other filter cartridges in a rotatable drum assembly whereby a clean filter can be rotated into position to permit products of combustion to pass therethrough while dirty filters are rotated to a position where they can be cleaned automatically for reuse.

ttes

288.3 F, 288.3, 2.2; 55/DIG. 30, 512, 400, 511, 523, 522, 285; 110/8 A, 8 E

[56] References Cited UNITED STATES PATENTS 2,285,804 6/1942 Campbell et a1 23/2883 X 2,843,217 7/1958 Von Linde 55/400 X 3,146,072 8/1964 Morgan 23/277 C 3,273,971 9/1966 Baddorfet a1. 231/2883 F Primary Examiner-James H. Tayman, Jr. Attorney- Brown, Murray, Flick & Peckham ABSTRACT: A smoke control system utilizing an afterburner and a filter formed from expanded blast furnace slag, the filter being in the form of a cartridge carried with other filter cartridges in a rotatable drum assembly whereby a clean filter can be rotated into position to permit products of combustion to pass therethrough while dirty filters are rotated to a position where they can be cleaned automatically for reuse.

V 2 5 4D 38 32 2Q 8 V 60 I 0 26 22 m v 4o 42 46 23 T CONTROL 28 CIRCUIT 2 POWER SOURCE I fill/IOKIE CUN'II'IRQIL SYSTEM BACKGRQUND TO THE INVENTION Various systems have been developed for eliminating or reducing pollution of the air. Many of these involve electrostatic precipitation techniques; and some use afterburners wherein smoke is further burned in a chamber beyond main fire box in an attempt to effect complete combustion thereof. Most of these systems, however, are expensive and not altogether effective. Gther systems have used filters; but this normally entails the problem of frequent replacing and/or cleaning of the filter units.

SUMMARY OF THE INVENTION In accordance with the present invention, smoke control apparatus is provided comprising means for directing smoke to an afterburner which is preferably heated by an electric coil. In the afterburner, the smoke is agitated into a turbulent condition to effect complete combustion of any combustible materials and thereafter passes through a filter, formed from expanded blast furnace slag. From the filter, the gases pass through a blower and thence through a second slag filter back to the stack. Alternatively, all or a portion of the gases can be recycled through the afterburner and the filters before passing to the stack and the atmosphere.

In one embodiment of the invention shown herein, the two filters are carried in a rotatable drum containing a larger number of filters such that upon rotation of the drum, a clean filter will be rotated into alignment with a conduit conveying the gases, while a dirty filter is rotated to a position where it may be automatically flushed with water or another solvent to clean it. Thereafter, upon further rotation of the drum, the clean filter is again rotated back into alignment with a conduit conveying the gases passing from the afterburner. In this manner, the filter cartridges need not be replaced; however, at the same time, a clean supply of filters is always available, and the filters can be changed by simply rotating the aforesaid drum.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. I is a schematic illustration of one embodiment of the invention; and

FIG. 2 is an end view taken substantially along line IIII of FIG. I showing in detail the rotatable drum assembly which carries the filter cartridges utilized in the invention.

With reference now to the drawings, and particularly to FIG. I, the apparatus of the invention includes a stack through which smoke passes from a firebox, now shown, upwardly along the direction of arrow 12. Positioned within the stack 10 and at the top thereof are hoods MIA-14E. The goods M A-ME are connected through a common conduit 16 and a valve 18 in the inlet of an afterburner 20 containing an electrical heating coil 22 connected to a suitable source of electrical power 2ll through a control circuit 23. The forward end of the afterburner 20 is provided with an opening 2d of relatively small size fitted with a seal 26 which abuts against a rotary drum 28, perhaps best shown in FIG. 2.

The drum 28, preferably formed from sheet metal or the like, carries a plurality of canisters MIA-30E circumferentially spaced around the axis 32 thereof. Each canister SIM-30E is filled with expanded blast furnace slag 34; while its end are covered with wire mesh material, generally indicated by the reference numeral S6 in FIG. 2. The ends of the canisters 30A-30E adjacent the afterburner 20 are provided with openings of a size to conform to the opening 24 in the afterburner.

The side of the drum 28 opposite the afterburner 20 is provided with openings which register with the canisters 30A-30E and are adapted to be rotated into alignment with a conduit 38 having a suitable seal 40 which rides against the face of the drum 28. Thus, hot gases, as they pass from the afterburner 20, will travel through the expanded blast furnace slag in one of the canisters and thence into the conduit 38 which leads to the inlet of a blower 42. The outlet of the blower 42 is connected through conduit 44 back through the expanded blast furnace slag in a second canister.

In FIG. 2, the locations of the two canisters which are aligned with the conduits 38 and 4d are indicated by the reference numerals 30A and 308, respectively. With the canisters 30A and 3013 in the positions shown, a third canister 30C is at the bottom of the drum 28:; and in this position the filter cartridge containing the expanded blast furnace slag may be cleaned by means of a water jet generally indicated by the reference numeral 46 in FIG. ll.

In the operation of the device, two of the filter cartridges (i.e., canisters 30A and 30B) are aligned with the conduits 38 and 44 while filter cartridge within canister 30C at the bottom of the drum 28 is cleaned by the water from jet 4%. Upon rotation of the drum 28 in the direction of arrow 48 shown in FIG. 2, the clean filter within the canister lltlC will be rotated up into alignment with the conduit 38 while a dirty filter will be rotated out of alignment with conduit 44 and into the position identified by the reference numeral MD in FIG. 2. The drum 28 will then remain in this position until the filters become dirty; whereupon continued rotation of the drum 28 in the direction of arrow 38 will rotate a clean filter into alignment with conduit 38 while a dirty filter is cleaned at the bottom of the drum. If desired, the spray from jet 46 may contain calcium carbonate which, when the filter is rotated into alignment with conduit 38, will convert into calcium oxide which assists in the elimination of impurities in the gas passing therethrough.

The conduit 44 is provided with a seal 50 which abuts against the side of the drum 28. The other side of the drum opposite the conduit 44 is provided with a conduit 52 also provided with a seal 54. Conduit 52 is connected through valve 56 back to the stack 10; and also may be connected through a bypass 58 containing a valve 60 back into the inlet of the afterburner 20. The gases passing back into the stack It) stir up any soot therein and help keep the chimney clean.

In operation, the blower $2 is started, thereby creating a partial vacuum within the afterburner 20 which, assuming that the valve 118 is open, sucks smoke collected by the hoods MIA-ME into the afterburner. By virtue of the fact that the afterburner, at its forward end, is provided with a reduced diameter opening 24, the smoke-laden air entering the afterburner is agitated into a turbulent condition and subjected to the heat of the coil 22. This causes combustion of any unburned combustible materials in the smoke. Optimum performance may be obtained by adjusting the power supplied to coil 22 via control circuit 23. Thereafter, the smoke will pass through a filter cartridge 30A-30E in drum 28, through the blower 42 and conduit 44, through a second filter cartridge and thence through conduit 52 and valve 55 back to the stack 10. Alternatively, however, some of the gaseous material in the conduit 52 may be returned to the inlet of the afterburner 20 to be recycled. Suitable manipulation of the valves I8, 56 and 60 will provide complete elimination of smoke from the top of the stack 10. This can be observed visually, as will be understood.

As was mentioned above, the canisters MIA-30E in the drum 28 contain expanded or lightweight slag which is the foamed product produced when molten slag is expanded by applying a limited quantity of water. The product contains a large number of small holes, thereby providing a large surface area for the collection of impurities in the gas stream. At the same time, however, the slag can be washed easily by water to remove the impurities; and large amounts of smoke can be eliminated without the necessity for changing filters.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing form the spirit and scope of the invention. In this respect, it will be apparent that the invention can be used with equal effectiveness in purifying exhaust from internal com bustion engines.

I claim as my invention:

1. in a smoke control system, the combination of an afterburner, means for directing smoke-laden air into said afterburner, heating means within said afterbumer for burning combustible materials in said smoke-laden air, filter means connected to the output of said afterbumer and through which gases from said afterbumer must pass, said filter means comprising at least three filter elements containing slag as a filtering medium and circumferentially spaced around a rotatable drum, conduit means for conducting gases through one of said filter elements and then through a second of said filter elements, and means for conducting a cleaning medium through a third of said filter elements while two of said filter elements are in use with gases from said afterbumer passing therethrough,

2. The smoke control system of claim 1 wherein said afterburner has an exhaust opening of reduced size whereby a turbulent condition of the gases will be produced in said afterburner.

3. The combination of claim 1 wherein said heating means within the afterbumer comprises an electrical heating coil.

4. In a smoke control system, the combination of an afterbumer, means for directing smoke-laden air into said afterburner, heating means within said afterbumer for burning combustible materials in said smoke-laden air, filter means connected to the output of said afterbumer and through which gases from said afterbumer pass, said filter means comprising a rotatable drum having a plurality of filters circumferentially spaced around the periphery thereof whereby upon rotation of the drum successive filters will be moved into registry with the outlet of said afterbumer, a blower connected to the side of said filter means opposite said afterbumer and including conduit means for conducting gases after passing through said blower through a second filter in said rotatable drum, and means for recirculating hot gases through said afterbumer after they have passed through said filters.

5. The combination of claim 4 wherein said means for directing smoke-laden air into said afterbumer comprises a plurality of hoods disposed within a smoke stack.

6. The combination of claim 5 including conduit means for returning the gases to said smoke stack after passing through i said afterbumer and said filter means. 

2. The smoke control system of claim 1 wherein said afterburner has an exhaust opening of reduced size whereby a turbulent condition of the gases will be produced in said afterburner.
 3. The combination of claim 1 wherein said heating means within the afterburner comprises an electrical heating coil.
 4. In a smoke control system, the combination of an afterburner, means for directing smoke-laden air into said afterburner, heating means within said afterburner for burning combustible materials in said smoke-laden air, filter means connected to the output of said afterburner and through which gases from said afterburner pass, said filter means comprising a rotatable drum having a plurality of filters circumferentially spaced around the periphery thereof whereby upon rotation of the drum successive filters will be moved into registry with the outlet of said afterburner, a blower connected to the side of said filter means opposite said afterburner and including conduit means for conducting gases after passing through said blower through a second filter in said rotatable drum, and means for recirculating hot gases through said afterburner after they have passed through said filters.
 5. The combination of claim 4 wherein said means for directing smoke-laden air into said afterburner comprises a plurality of hoods disposed within a smoke stack.
 6. The combination of claim 5 including conduit means for returning the gases to said smoke stack after passing through said afterburner and said filter means. 